<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    const arr = [1,2,3,4,5]
    Array.prototype.MyforEach = function (cellback){
      for(let i=0;i<this.length;i++)
    //    console.log('666',this[i]);
      cellback(this[i],i,this)
     
    }
    const res = arr.MyforEach((item,index,arr)=>{
        console.log(item,index,arr);
    })
    console.log(res);
</script>
</html>